w3schools Logo
Monday 21 May 2012
W3schools.in Developer Network

MySQL Database

MySQL Introduction MySQL Connect DDL, DML and DCL commands? Database Normalization MySQL Create MySQL Insert MySQL Select MySQL Where MySQL Join MySQL Order By MySQL Update MySQL Delete

PHP Tutorial

How to Learn PHP PHP Home PHP Intro PHP Syntax PHP Variables and String PHP Operators PHP Date and Time PHP If...Else PHP Switch PHP Arrays PHP Looping PHP Functions PHP $_GET and $_POST PHP String Manipulation PHP Form Validation PHP Include PHP Files PHP File Upload PHP Cookies PHP Sessions PHP E-mail PHP Interview Questions

PHP Example Scripts

PHP MySql Resume management script Javascripts/Css Date Picker script Css Pagination Styles Sample Blog with user management and admin PHP Forum & Discussion Board Scripts PHP Captcha

 

PHP Tutorials Lessons

PHP MySQL Introduction

php scriptsPHP and MySQL are a good combination for creating an ecommerce solution for your website.

MySQL Databases

MySQL is the most popular Open Source Relational SQL database management system.

MySQL is one of the best RDBMS being used for developing web based software applications. 

MySQL database application should be installed on your web server. MySQL is very popular so you will have no problem in finding a web host that offers MySQL. Most web host also offer a (GUI) Graphical user interface application such as PHPMyAdmin for working with MySQL databases.

Relational DataBase Management System (RDBMS)

  • RDBMS you to implement a database with tables, columns, and indexes.

  • Guarantees the Referential Integrity between rows of various tables.

  • Updates the indexes automatically.

  • Interprets an SQL query and combines information from various tables.

RDBMS Terminology:

Before we proceed to explain MySQL database system, lets revise few definitions related to database.

  • Database: A database is a collection of tables, with related data.

  • Table: A table is a matrix with data. A table in a database looks like a simple spreadsheet.

  • Column: One column (data element) contains data of one and the same kind, for example the column postcode.

  • Row: A row (= tuple, entry or record) is a group of related data, for example the data of one subscription.

  • Redundancy: Storing data twice, redundantly to make the system faster.

  • Primary Key: A primary key is unique. A key value can not occur twice in one table. With a key you can find at most one row.

  • Foreign Key: A foreign key is the linking pin between two tables.

  • Compound Key: A compound key (composite key) is a key that consists of multiple columns, because one column is not sufficiently unique.

  • Index: An index in a database resembles an index at the back of a book.

  • Referential Integrity: Referential Integrity makes sure that a foreign key value always points to an existing row.

MySQL is becoming so popular because of many good reasons:

  • MySQL is released under an open-source license. So you have nothing to pay to use it.

  • MySQL is a very powerful program in its own right. It handles a large subset of the functionality of the most expensive and powerful database packages.

  • MySQL uses a standard form of the well-known SQL data language.

  • MySQL works on many operating systems and with many languages including PHP, PERL, C, C++, JAVA etc.

  • MySQL works very quickly and works well even with large data sets.

  • MySQL is very friendly to PHP, the most appriciated language for web development.

  • MySQL supports large databases, up to 50 million rows or more in a table. The default file size limit for a table is 4GB, but you can increase this (if your operating system can handle it) to a theoretical limit of 8 million terabytes (TB).

  • MySQL is customizable. The open source GPL license allows programmers to modify the MySQL software to fit their own specific environments.

Sun to Acquire MySQL

MySql was previously available on open source but knowing its utility it was purchased by Sun Microsystems.

Read More:

http://www.mysql.com/news-and-events/sun-to-acquire-mysql.html



W3
2009-12-15 13:12:03 887day

What is advantages of DBMS? 
ans-
1. Redundancy is controlled. 
2. Unauthorized access is restricted. 
3. providing multiple user interfaces. 
4. Enforcing integrity constraints. 
5. Providing backup and recovery.

 

W3
2009-12-15 13:12:02 887day

Disadvantage in File Processing System?
ans-
1. Data redundancy & inconsistency. 
2. Difficult in accessing data. 
3. Data isolation. 
4. Data integrity. 
5. Concurrent access is not possible. 
6. Security Problems.

 

W3
2009-12-15 13:12:53 887day

The three levels of data abstraction 
1. Physical level: The lowest level of abstraction describes how data are 
stored. 

2. Logical level: The next higher level of abstraction, describes what data are 
stored in database and what relationship among those data.  

3. View level: The highest level of abstraction describes 
only part of entire database. 


Data independence means that “the application is independent of the storage structure and access strategy of data”.
In other words, The ability to modify the schema definition in one level should not affect the schema 
definition in the next higher level.  

Two types of Data Independence:  

1. Physical Data Independence: Modification in physical level should not affect the logical level.  
2. Logical Data Independence: Modification in logical level should affect the view level.  
NOTE: Logical Data Independence is more difficult to achieve 


- DDL (Data Definition Language)  
A data base schema is specifies by a set of definitions expressed by a special language called DDL.  

- VDL (View Definition Language)  
It specifies user views and their mappings to the conceptual schema. 

- DML (Data Manipulation Language)  
This language that enable user to access or manipulate data as organised by
appropriate data model.  
1. Procedural DML or Low level: DML requires a user to specify what data are needed
and how to get those data.  
2. Non-Procedural DML or High level: DML requires a user to specify what data are needed
without specifying how to get those data 

 

Cabdi yusuf
2010-01-20 20:01:43 851day

iam very gratefull this tutorial so iam very favorite

 

Amit Nashikkar
2010-05-21 14:05:29 730day

good Site

 

Geetha
2011-02-17 10:02:57 458day

MySQL uses indexes for these operations:

    * To find the rows matching a WHERE clause quickly.
    * To eliminate rows from consideration. If there is a choice between multiple indexes, MySQL normally uses the index that finds the smallest number of rows (the most selective index).
    * To retrieve rows from other tables when performing joins. MySQL can use indexes on columns more efficiently if they are declared as the same type and size. In this context, VARCHAR and CHAR are considered the same if they are declared as the same size. For example, VARCHAR(10) and CHAR(10) are the same size, but VARCHAR(10) and CHAR(15) are not. 

 

Shreyas Patel
2011-03-27 11:03:56 420day

However its Amazing Really

 

ARVIND
2011-05-29 22:05:27 357day

very good site and also very helpful

 

Hardik
2012-04-28 17:04:15 22day

this site is really helpful for freshly graduated students and Developers...thanks a lot for this site... really appreciable work...

 

Add Comments / Scripts
Name:
E-mail:
Comment:
 


Can't read the image? click here to refresh